Air Monitoring

The ultimate goal of the Pima County Department of Environmental Quality (PDEQ) air quality control program is to reduce harmful contaminants in ambient air to healthy levels, and maintain those levels. A key process in controlling air pollution is to define the nature and extent of air quality problems through monitoring. Pima County is currently in attainment of all U.S. EPA National Ambient Air Quality Standards, however, this region is very close to non-attainment of the EPA ground-level ozone standard.

PDEQ monitors six criteria pollutants in the Tucson and Green Valley area in accordance with regulations established by the Environmental Protection Agency (EPA). Data is reported hourly here, to the EPA's Air Now website and other agencies. An Air Index Now report, based on the Air Quality Index (AQI), is generated hourly for public notification of current air quality conditions and possible health effects. Below are the current AQI values.

Besides the tabs below the Information, Education, Public Outreach and the Clean Air Program area will have additional information about air quality. As part of its role in the community, PDEQ staff offers educational, regulatory and professional group tours of its air quality monitoring facilities. Many schools utilize these tours in their curriculum. Please call our Community Outreach Contact, at (520) 724-7400 for more information on this service. Notify us if you would like to receive air quality advisories and related information. Thanks to a collaborative effort between the Arizona Department of Environmental Quality (ADEQ) and PDEQ a 5-day air quality forecast for the Tucson Area is available from ADEQ.

Air Quality Index

The Air Quality Index is the uniform procedure by which daily air pollution levels are reported to the public. AQI levels are set by the Environmental Protection Agency in accordance with section 319 of the Federal Clean Air Act.

Air quality information is collected by the Pima County Department of Environmental Quality monitors located throughout Eastern Pima County. The monitors collect concentration information in parts per million and parts per billion for gases and micrograms per cubic meter for particulates. The level of pollution in the air and the related health effects are relayed to the public using the Air Quality Index. If a pollutant such as ozone has an AQI value of 59, the corresponding qualitative descriptor would be MODERATE. The AQI value of 100 generally corresponds to the National Ambient Air Quality Standard for the pollutant. AQI values below 100 are considered satisfactory while numbers above 100 are considered to be unhealthy.

The AQI is the highest value for the pollutant in a 24-hour period. The highest 8-hour average for ozone and CO, and the highest 24-hour average for PM10 and PM2.5 . This report is used for daily statistics and historical summaries.

The Air Index Now is used for the hourly updates of what the public is breathing at that moment. This index is calculated using modifications to the AQI to give the most accurate estimate of what is in the air at that particular point in time.

When air quality levels are elevated you can sign up to receive our advisory notifications. Please call our Community Outreach Contact at 724-7400 for this service.

Air Pollution Data

Please note: Many of these reports display values for 1-hour PM10 and PM2.5 (particulate matter 10 and 2.5 microns or less in diameter) concentrations. These data values are provided for informational purposes only. The EPA Health Standard for PM10 and PM2.5 is a 24-hour standard, based on the average of 24 hourly readings from midnight to midnight. The EPA has not yet developed a 1-hour standard for PM10 or PM2.5.

Historic 24-Hour Particulate Data:

Quality Assurance of Air Pollution Data

Local agencies such as PDEQ involved in federal monitoring programs must comply with federal air quality assurance requirements. Each agency must develop and implement a Quality Assurance (QA) program consisting of policies, procedures, specifications, standards, and documentation necessary to:

Provide data of adequate quality to meet monitoring objectives, and

Minimize loss of air quality data due to malfunctions or out-of-control conditions.

It is the policy of PDEQ to conduct and support appropriate quality assurance activities to ensure that these objectives are met.

Monitoring Information

Pima County Department of Environmental Quality and its predecessors have conducted air monitoring in the Tucson, Arizona area since the 1960's. PDEQ monitors ambient (outdoor) air pollutants at 16 monitoring stations located throughout eastern Pima County, including the Tucson metropolitan area and Green Valley. More information regarding PDEQ's air monitoring program is available in the 2016 Ambient Air Monitoring Network Plan.

There are six principal pollutants, called “criteria” pollutants that are monitored in accordance with the National Ambient Air Quality Standards (NAAQS) set by the Environmental Protection Agency (EPA) to comply with the Federal Clean Air Act. The NAAQS were established to protect public health and the environment from harmful levels of air pollution.

In addition, PDEQ conducted a special Beryllium Monitoring Study to determine levels of beryllium in the air surrounding the Materion Ceramics (formally Brush Ceramics) facility in Tucson.

The air quality monitoring section is divided into 3 units; the Field Monitoring unit, the Data Management unit and the Quality Assurance (QA) unit. The field monitoring unit conducts all quality control procedures related to routine operations such as calibrations, equipment checks, troubleshooting and repair of equipment necessary for air quality monitoring. The data management unit handles all operations related to network operations, data acquisition, management, storing and reporting of data. The QA unit operates independently of the field monitoring unit to assure the quality and accuracy of the data recovered.

Almost all routine air quality monitoring data generated by PDEQ are submitted to the U.S. Environmental Protection Agency (EPA) AQS database system. Most air quality monitoring stations in the PDEQ network are equipped with electronic data loggers designed specifically for the logging of air quality data.

The data loggers are programmed to take the electrical outputs from air quality monitoring instruments at a monitoring station and transmit this information via a modem to a central computer data acquisition system (DAS) located in the PDEQ offices. This information is then validated to detect possible erroneous readings, and stored in a central database. The information is then reported to the EPA, documented in summary reports, and made available to local agencies, researchers and the public.

Reports

2016 Air Quality Summary Report -Summary of air quality monitoring data and trends in Pima County for the previous year (updated every summer for the previous calendar year).